Definitely not new. St. Francis of Assisi, Leonardo Da Vinci, Pythagoras, and many other thinkers have had something to say on the ways humans use animals.

My favourite old school animal rights thinker was blind rebel vegan poet Abul ʿAla Al-Maʿarri who lived 973–1057:

And do not desire as food the flesh of slaughtered animals,

Or the white milk of mothers who intended its pure draught

for their young, not noble ladies. [...]

I washed my hands of all this; and wish that I

Perceived my way before my hair went gray!

More on him: http://www.archive.org/stream/journalroyalasi48irelgoog#page/n704/mode/2up http://www.archive.org/stream/studiesinislamic00nichuoft#page/134/mode/2up

Edit: formatting.